Mana Regeneration
The condition of a game character gaining mana points over time is referred to as''mana regeneration''. There are several sources of mana regeneration, each with their own characteristics. Spirit-based regeneration All characters with mana points passively regenerate some mana in ticks of 2 seconds. The amount of mana gained per tick is based on the character's class and spirit attribute, according to the following formulas: From these formulas it follows that increasing a character's spirit yields constant returns for mana regenerated per tick. Druids'in Patch 2.0 Crusade now receive spirit/'4.5+ 15 but only in biped form. Whilst shapeshifted they still receive spirit/'5'+ 15 Five Second Rule After a character expends mana in casting a spell, the effective amount of mana gained per tick from spirit-based regeneration becomes a ratio of the normal listed above, for a period of five seconds. During this period mana regeneration is said to be''interrupted''. This is commonly referred to as the 'five second rule'. Channeled spells are handled a little differently. The five second rule starts when the spell's channeling starts; i.e. when you pay the mana for it. The rule continues for at least five seconds, and longer if the spell is channeled for more than five seconds. For example, Mind Flay channels for 3 seconds and interrupts your regeneration for five seconds, while Tranquility channels for 10 seconds and interrupts your regeneration for the full 10 seconds. By default, your interrupted mana regeneration ratio is 0%, meaning that spirit-based mana regeneration is suspended for five seconds after casting. Several effects can increase this ratio, including: Note that spells which don't cost mana will not start the five second timer and will let you continue regenerating mana.Nature's Swiftness costs no mana, and thus will not invoke the five second rule. Spells cast with the Clearcasting state will also not start the five second timer. Totems, on the other hand,''will''start the five second timer. Prior to the 1.4.0 patch, you also did not regenerate mana during the casting of the spell. In-game textual references to the five second rule still read "while casting" where they actually should read "after casting". Direct regeneration Many effects increase mana regeneration directly i.e. without increasing spirit. These effects are governed by different rules than spirit-based regeneration. Mod Power Regen effects Most items which restore mana, including various types of water as well as equipable items such as Anathema, works similarly to spirit-based regeneration in that they regenerate mana in ticks of 2 seconds. Unlike the spirit-based regeneration, however, the five second rule does not apply to these effects. That is, after casting a spell, mana regeneration from these items will continue. This can make a difference in fights, where long chains of uninterupted spell casting both drains mana and halts spirit-based regeneration. Periodic Energize effects A few items, such as Second Wind, as well as some spells, like Blessing of Wisdom, does not regenerate mana in 2 second ticks but rather in the intervals actually advertised in their tooltips. The five second rule does not apply to these effects either. Comparing spirit based and direct regeneration In theory, direct regeneration is preferable over spirit-based regen, as it is not subject to the five second rule. If for example a priest could give away 8 spirit, and gain 5 mana/5, the latter would give the same regen as the spirit at all times, and thus be better (disregarding HP regen). The factor where spirit and mana/5 give the same base amount of regen (outside the five second rule) is 1.6 spirit for 1 mana/5 for priests and mages, and 2 spirit for all others. The correct way to find out which is better would be to find your personal percentage spent inside the five second rule, e.g using an addon like Muse. Knowing the percentage, you now have a base to compare the relative merits of different item sets with high accuracy. A simpler approach can be found using the Item Values article, where an attempt is made to reverse-engineer the factors Blizzard uses when creating Items. These factors can be understood as a kind of price tag for item properties. According to that analysis, 1 mana/5 has the same "cost" as 2.4 spirit. Comparing items of otherwise similar properties, the only difference being that one has spirit and the other mana/5, mana/5 gives mages and priests (1.6/2.4 =) 66% of the regen which they would get from spirit. All other classes get (2/2.4 =) 83% of the spirit regen. Be aware that these percentages are only valid if you compare items which are otherwise very alike. Example: Comparing Tooth of Gnarr and Seal of Rivendare. According to the Item Value analysis, items on neck and finger are directly comparable. The stats on both items have nearly the same value. The 3 mana/5 from the Tooth needs to be compared to a spirit regeneration of 4.4 mana/5 for Mages and Priest, and 3.5 mana/5 for all other classes. The other classes face a rather easy decision, since it's highly probable that they will spend more than 15% of the combat time inside the five second rule, whereas Mages and Priests would have their break-even point at 32%, offering no clear solution. Additional notes * You do not regenerate mana faster if you are sitting down or standing up. * Spell casting never stops direct mana regeneration effects from items.